Shared hosting is when you have your hosting account on a server(computer) with other peoples websites that are managed by a professional server administrator. This not only saves a lot of money for websites just starting out but it can also be more secure then running your own server. The server company is tasked with securing the server, providing updates for the server, and securing the server, so you don’t have to. Better yet this is at a fraction of the price of what you would have to pay if you had your own server.
The draw back to being on a shared server is, that you are with other people. And just like in real life, not everyone is polite. So some people may use more resources on the server then they are supposed to or more bandwidth then they should and cause your site to be slow or lag. So that can defiantly be a draw back to shared solutions. But the benefits of being on a shared hosting can often out weigh the disadvantages by a long shot, especially if your with a major provider that has proper control over their servers.
Some things to look for is to see if they are using cloud or grid based technologies in their servers. this is normally a good sign they have the ability to thwart those noisy neighbors, and keep your site both up, and not lagging as well.
There are many things you should look at when picking a shred hosting company such as price, reputation, and server up time as well as support options, so don’t forget those. But the technologies being used are a big deal when it comes down to the success of your website.